Electric head lamp projector and incandescent lamp therefor



Filed Sept. 28, 1944- Nov- 30. 1 4 R R. K. BRAUNVSDORFF I 2,454,765

ELECTRIC HEADLAMP PROJECTOR AND INCANDESCENT LAMP THEREFOR 2Sheets-Sheet 1 REGINALD K. BRAUNSDORFF Nov. 30, 1948. R. K. BRAUNSDORFF.

ELECTRIC HEADLAMP PROJECTOR AND INQANDESCENT LAMP THEREFOR Filed Sept.28,1944

FIG.

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2 Sheets-Sheet 2 INVENTOR.

REGINALD K BRAUNSDORFF M w m wet 7,.

Patented Nov. 30, 1948 UNITED STATES 2,454,? 65 C J HEA i rj ditQTiiiiAi 'I'NCANDESCENT LAlWP THE REFOR- I Reginald K. Braunsdo'rfi,Eli-stowage, N. 1-; e5 signer to Tung- S0l Lamp WorksJ-nc Newark,- N. Ja corporationof Delaware Application September 28, 1e44,-serieiiibsesegiis 3.! Claims. .1 This invention relates to electricheadlamp projectors and incandescentlamps therefor.

' A parabolic reflector with a point fig t-source at the focus wouldgive a circular parallel team of reflector diameter. A point source isnot available in practice as all conventional filamentspossess mass andsize which disturbs such theorectical projection. lhe size of thefilament (which includes number of turns, length er barrel and diameterof coil) influences the spot or beam pattern obtained. Different kindsof reflectors have been proposed and various lenses have'been proposedfor modifying the beam or batte'rri furnishedby the reflector.

One object of the invention is an incandescent filament lamp forreflector or headlightus'e emb'odying a coil filament of distorted formfor oldtaining a headlight beam pattern which appr icimates more nearlythe desired pattern thereby minimizing the importance or neeessity'rerthe provision of a special modifying lens.

A further object of the invention is anelec trio incandescent lamp ofthe bove ifidic'atec l character having ac'ontinuo'iis coilfilamehtwhich is distorted or irregularly formed at different portionsof its length and may be wound en -e single mandrel ate singleoperation.

A further object or the invention is a coinbified reflector of theconventional paraboiiero'rni and an electric incandescent lampsourceoftl ie abov'e indicated character mounted in the reflector so asto assist in obtaining the desired beam fiat tern.

Further objects of the invention Will -herein after appear.

For a better understanding of the invention, reference may be had to theaccompanying draw ing, forming a part of this application-where Fig. 1is a View diagrammatically illustrating one embodiment of the invention;

Fig. 2 is a diagrammatic view of another mode fication of the inventionv Figs. 3 to 8 are diagrammatic viewsof other modifications of theinvention;

Fig. 9 is; a diagrammatic view of an electric incandescent lamp of thegeneralcharacter shown in Fig.1 mounted in aconventional parabolicreflector, together with a beam pattern which may be approximated bysuitably mount-'- A ing the lamp in the" reflector;

Fig. 10 is a similar diagrammaticview of an incandescent lamp of thegeneral character shown in Fig. 2; and l r Fig. 11 is a View of a stillfil'i'thei I For vehicle roa'd. lightinggeneralli a beam pattern 18desired which is cut off in the upper le'ft sectioi ilookingin thedirection of travel so as *o Iifififid' lower liglfiit Output in theupper left section, and higher light output inthe upper rig-lit sectionTwo" shapes of such beams are shown drag mriia itically in Figs. 9b1-01) Brit ridersto'od that these 'beanis' thusschemati "OWIi are iriterided t illustrate may the shap' a-lld not aeeu reten" to ihd'iait theei'ac't details of fliebea'lrripattern.

The pattern- Fig. 9b is or sun i'itafitlally' less "depth ontl'i 'lftthan it is onthe right; Siic a. Idea-in may be approximated by d oflarger coi-ldiameter at its *leftliand and looking dawn the reflector.The filathe r thateiiibodime'fit is er inultipie e011 di parts, therebeing two such parts 3 and the particular embodiment shown the if) ts 3and 4 or the mamentnave a; common ax s (Fig; I) Edd-the 1561 1; 3 islor'l'gl" than the ""e tiriis the length thereof 7, three times" the Vdin-the larger end 4 of the filamen e iennye lengths er distorted baitsor the easiest z be varied to the reqiiire'rnents, fer 'ei'z'a'r'x inle,the large part-4 in 1 sateen; Figs The at 2 e minate in the bulb or envegne 5 and the lamp" than resumes-in the refle er l Se-sets nfiodu'ce oraeeressinate tne desired-ff r xa'" le', by l ios'itidfiirrg I to h tfilament 2 hear ""ga de'fir'iite re atiori t'e' the-fecal point of theraise-ceases for exam-ere, with the focal iioint o'f-th reflectordisfaosdintermediate the length of tneeeii 2 and on the common axisthereof. A bam pattern geeeiam like t-at snows in Fig. 96 may beapereetnea naving enlarged part 4 on the right ariart of smaller depth3' on the left, rocking the difectidii-of the'projcted beam. Theenlarged part 4' of the beam pattrn isercedeen by the part 4 or thelarger diameter fior'tidii o'f th dis'torted filament'but th epiiesite'side or forward vertical iilan'e 1i sing tnronghtne focal point ofthereflector, and-similarly th sinali tairt of the beain' pattern 3 isproduced by the small diameter part 3 of the distorted filament butlikewise on the opposite side of that vertical plane. As above pointedout, the beam pattern shown in Fig. 9b is not intended to be an exactmathematical illustration of the actual beam produced but is intended asan illustration merely of the general shape contrasting the widelyvarying parts of the pattern. in Fig. 9 the lamp is mounted in thereflector I with the common axis of the filament 2 disposedsubstantially horizontal but by orienting the lamp so as to incline thisaxis of the filament 2 to the horizontal plane the parts 3' and 4 of thebeam may be varied in a vertical plane relatively to.

each other, as for example so as to elevate the righthand portion 4 ofthe beam pattern with respect to the parts 3, thereby bringing thebottom edge of the pattern to approximately the horizontal position.Likewise different beam pattern effects may be obtained by shifting thedistorted filament 2 with respect to the focal point of the reflectorand by combining these two adjustments other beam pattern effects may beproduced.

In the embodiment of Fig. the beam pattern shown in Fig. 19?) has acommon bottom cut-off line 6 for both the right and left hand parts ofthe beam, with the filament l disposed substantially horizontal. A beamof this general shape, looking in the direction of the beam projection,may be approximated by distorting the shape of the filament l as shownin Figs. 2 and 10a. In this embodiment the filament coil is alsoprovided with different coil diameter parts at its ends, the right-handpart 8 of the filament being of small diameter, while the part 9 on theleft is of relatively larger diameter, but here the axes of the twofilament parts 8 and 9 are relatively offset with the edges of the turnsof the parts 8 and 9 being disposed in line on one side. In Fig. 2 theaxis of the part 9 of the filament is shown in broken lines while theaxis of the part 8 of smaller diameter is illustrated in a dot-and-dashline. The part 9 of the filament assists the reflector in producing thepart 9"of the beam pattern, while the part 8 assists in producing thepart 8 of the beam pattern (Fig. 10b); The focal point of the reflectorI may be disposed roughly midway the length of the filament coil 7 andbetween thev axes of the coil parts 9 and 9 and by the use of aparabolic reflector I or reflector generally of that construction or ofthe conventional type, the beam pattern parts corresponding to theparticular parts 8 and 9 of the filament are produced on the oppositesides of the vertical plane passing through the axis ofthe reflector.This pattern corresponds generally to the positioningof the filamentabout the focal point as described, with the axis of the filament part 9disposed below the axis of the filament part 8, namely with the filamentpart 9 being predominantly below the horizontal plane through the axisof the reflector, while the filament part 8 is generally symmetricalwith respect to that plane. The pattern may be varied by mounting thefilament in the reflector so as to have the axes of the filament partsoffset from each other in any desired direction.

The pattern shown in Fig. 10b may be varied by changing the filament 1relatively to the focal point, that is by changing the vertical orhorizontal positioning with respect to the focal point or by acombination of these adjustments In the particular embodimentillustrated or by rotation of the bulb 5 about its axis in thereflector. In the particular embodiment shown the length of the smalldiameter part 8 is greater than the length of the large diameter part 9and also in this particular embodiment the part B has roughly twice thenumber of turns and is roughly twice the length of the large diameterpart 9 but it is understood that the number of turns of each of theparts 8 and 9 may be Varied to suit any particular requirements.

In the embodiments illustrated in Figs. 1, 2, 9 and 10, the diameter ofthe filament parts 3 and 8 is roughly one-third the diameter of thelarger diameter parts 4 and 9 respectively of the filaments. Also in theparticular embodiments shown the filaments are constructed with steps indiameter, as distinguished from tapered coils with a uniform variationin diameter from one end to the other. But it is understood that certainadvantages of the invention may be obtained with variations in thestructure of the filaments, the relative arrangement thereof withrespect to themselves and to the focal point of the reflector, etc.

The filament embodiments of Figs. 3 to 8 show different forms ofcontinuous coil distorted fila ments. In Fig. 3 the parts 8 and 9 of thefilament 1 are like the embodiment of Fig. 2 shown of uniform diameterturns but are reversely positioned with respect to that illustrated inFig. 2. In Fig. 3 the axis of the part 8 which is illustrated in dot anddash lines is illustrated to be displaced with respect to the axis ofthe part 9 which is illustrated in broken lines, which is in reverseposition of that shown in Fig.2.

In the embodiment of Fig. 4 the continuous coil distorted filament Illhas its turns gradually increasing in diameter from the small end II tothe large end 12 and the increase in diameter is not uniform but theincrease in diameter is according to a mathematical curve as indicatedby the tangent CD touching the rearward edges of the filament turns. Theaxis of the filament I0 is shown in the dot-and-dash line.

In the embodiment of Fig. 5 the distorted filament I3 is provided withturns gradually increasing in diameter from the small end M to the largeend l5 and here the filament is unsymmetrical with respect to the axisEF of the small and of the filament, the axis FG of the filament l3being inclined to the axis EF and the rear edges of the turns formingthe filament coil are tangent to the vertical transverse plane parallelwith the axis EF. This is in contrast with the symmetrical filament IDof Fig. 4 whose turns are formed symmetrically about the axis EF of thesmaller end of the filament. In the em bodiment of Fig. 5 the axes EFand GF are illustrated as being in a plane parallel to the planedetermined by the legs A and B of the filament. In the embodiments ofFigs. 2 and 3 the axes of the filament parts 8 and 9 are also disposedin a plane parallel with the legs A and B. In the embodiment of Fig. 6the continuous coil distorted filament I6 is formed of two parts I! andi8 which parts are in turn formed of turns of uniform diameter similarlyto the embodiments of Figs. 1, 2 and 3. Instead, however of the axes ofthe filament parts I1 and I8 being coincident as in Fig. 1, they areoffset from each other but in a specifically different manner as shownby the lefthandp'art of Fig. 6, so that as viewed in the righthandportion of Fig. 6 the axes of the two parts I! and i8 appear to becoincident. Here the axis of the small diameter eateries:

5. part H of thefilament is parallel to the plane determined by the legsA and B andlikewise th'e axis of the large part IS. The centers of theparts H and I 8 are indicated respectivelyat and K in projectionto theleft of Fig. 6.

In the embodiment of Fig. 7 the filament 20 is provided with a smalldiameter part 2| and a larger diameter part 22 at the endswith anintermediate part 23. The part 2| is of uniform diameter and the part-22 is-of uniform diameter but the intermediate part 23 is of varyingdiam--'" eter so as to merge the end parts 21, 22 gradually intoeach'other. In the embodiment ofFig; 8 the filament 25 is formed of asmall diameteripart 26 and a larger diameter part 2Trespectivelyformedatthe ends. The small-diameter part 261s 'of uriiform diameter-turns.The larger diameter *part 2'! is formed with fiat-sided turns, the flatside being indicatedat 21'. Assuming "the mounting is such that the fiatside-of the large diameter part .2! is on the under side of the filament-25 shown in Fig. 8, theaxes of the parts 26'and 21 are displaced fromeach other in a vertical plane. In therighthand portion ofFig. 8 theseaxes'appear coincident. The sides of the turns of the small diameterpart 26 on one side are level with the surface of the fiat side 21' ofthe large diameter turns, that is the plane including the surfaces ofthefiatsides 21' of the part 2 istangent to the surfaces of the turnsforming the coil part 26. The ends of the axes of the two coil portionsarexindicated at H and K.

It is understood that the continuous coil 'dis torted filaments of Figs.3. to 8 are'mounte-d in a reflector of suitable type, asfor example, oneof the general parabolic type illustrated'by the numeral l in Figs. 9and 10. In each modification difiierent forms of beam patterns may beobtained by mounting the filament or lamp bulb 5 in the reflector insuch a manner as to obtain or approximate the desired shape pattern. Aswith the modifications of Figs. 1 and 2 (Figs. 9 and 10) different shapebeams may be obtained by mounting the filaments of each of themodifications 3 to 8 in different positions relatively to the focalpoint of the reflector and the axis of the beam pattern maybe adjusted.as may be desired by rotating the lamp bulb-5 within the reflector toobtain the desired orientation of the pattern.

In the particular embodiments illustrated I have shown bulbs -5embodying only aisingle distorted filament but in some cases it may bedesired to mount two of these distorted filaments in the same bulb withthe bulb mounted in the reflector so as to obtain a special beam patternformed by the combined lighting effect of the two or more distortedfilaments thus mounted with respect to the focal point of the reflectoror special beams from the individual filaments. Such a lamp bulb isillustrated in Fig. 11 wherein a bulb is shown embodying twoindependently mounted continuous coil distorted filaments, being similarto the filamentl of Fig; 1. It is'understood that the lamp bulb hereshown is mounted in a reflector of any suitable type, as for example, ofthe parabolic type indicated at l in Figs. 9 and 10 with the twodistorted filaments .30 and 31 positioned with reference to the focalpoint of the reflector as may be desired to obtain or approximate thebeam pattern desired.

Thus this invention makes it possible to obtain a beam pattern which issubstantially different from the beam pattern furnished by theconVentional filament lamps and accordingly an-initial beam distributionunassisted by lensactionds obtained which, together with the particularre fiectorused, is either sufiicienttogivethedesired beam pattern, "orless lens action is required to give the exact beam 'patterndesired,thereby simplifying' headlamp structures. In the particular embodimentshown in Figs, 1, '2, 9 and 10 the filament parts 3 and 8 of smallerdiameter are somewhat smaller than the diameters of the coil filamentsconventionally used in vehicle headlights, w'hilethe filamentp'arts 4and 9 are of substantially larger diameter.

The different embodiments of the invention indicate the wide variety ofpossible shapes of'continuouscoil-distorted filaments and thepossibilities of construction and flexibility afforded 'by theinvention. "Any part of the coil filament may be specially'constructedas for example, with a hat spot (Fig. 8) or with a raised section atsomeindivldilal'poin't Within the total coillength. The mass or spaceoccupied by the filament maybe varied together with its shape atdifierent points inorderto obtain the effect desired in the project-ionwith parabolic reflectors and the like. As above indicated theinherenterrorin projection maybe met by some special lens in the areawhich gave trouble in the projectedbeam but with my inventioncompensation may be made or approximated in the particular continuouscoil filament shape and in the particular position in which it ismounted in the bulb. Moreover, it is entirely practicable to formcontinuous coil filaments of the shapes indicated'by forming them'on-simi larly shaped mandrels.

In each of the Figures *1 to 8 the portion of the figure to the left isan approximate correct pro ject'ion of the largeend of the filament withcertain of the turnsoi the coil omitted in certain cases-tosimplify thedrawings.

Iclaim:

1. In an electric headlamp, a reflector, an in candescent lamp inthereflector having a lighting beam filament of the continuous coiltype, said filament having its end portions formed of different coildiameters and the whole filament being positioned in the vicinity of thefocal point of the reflector and at an angle to the axisof the lamp withthe different diameter end portions thereof disposed on the oppositesides of the re fiector axis.

2. In an electric headlamp, a reflector, an incandescent lamp havinga'lighting beam filament of the coil type, "said filament having its endportions formed of different coildiameters and the whole filament being"positioned in the reflector in the vicinity of its focal point and at anangle to the axis of the lamp with the diffierent diameter end portionsthereof disposed on the opposite sides of the reflector axis, and saidsmall diameter part having a larger number of turns than the number ofturns inthe larger diameter partlw i3. In an electric headlamp, areflector, an incandescent lamp having a lighting beam filament of thecoil type and mounted in said reflector, said filament l'having endportions of different "c'oikdiameters and the whole filamentibeingposiitioned in the" vicinity of the focal point of the reflector with'thefoc'altpoint disposed at the axis of the smaller coil section, saidfilament portions having a common axisand disposed at an angle to .the'axis of the lamp with the different diameter end portions thereofdisposed on the opposite sidesof thereflectoraxis.

:4. In an electric headlamp, a reflector, an ining beam filament of thecoil type, said filament having its end portions formed of differentcoil diameters and the whole filament being positioned in the vicinityof the focal point of the reflector, said filament parts having theiraxes offset with the different diameter end portions thereof disposed onthe opposite sides of the reflector axis.

. 5. In an electric headlamp, a reflector, an incandescent lamp thereinhaving a lighting beam filament of the coil type, said filament havingits end portions formed of different coil diameters and the wholefilament being positioned in the vicinity of the focal point of thereflector, said filament portions having their axes offset verticallywith the different diameter end portions thereof disposed on theopposite sides ofthe reflector axis.

6. In an electric headlamp, a reflector and an incandescent lamp sourcehaving a lighting beam filament of the coil type disposed in thevicinity of the focal point of the reflector with the barrel of the coildisposed at anangle to the axis of the headlamp, the coils at certainparts of the filament being of different diameters with differentdiameter portions disposed on the opposite sides of the axis of the lampso as to provide a filament at the focal point which is unsymmetricalwith respect to the axis of the lamp.

'7. In an electric headlamp, a reflector generally of the parabolic typeand an electric incandescent lamp source having a lighting beam filamentof the coil type with the whole thereof being disposed at or in thevicinity of the focal point of the reflecton said filament crossingtheaxis of the reflector at the focal point, said filament havingportions on the opposite sides of thereflector axis which areunsymmetrically distorted with respect to each other so as to give adistorted drive beam pattern.

8. In an electric headlamp, a reflector generally of the parabolic type,an incandescent lamp having a lighting beam filament of the continuouscoil type with the axis of the lamp being coincident with the axis ofthe reflector, the whole of said filament crossing the axis of thereflector at the'focal point and having end portions of different coildiameters with one end portion of the filament disposed on one side ofthe vertical axial plane passing through the focal point of thereflector and the other end portion of the filament disposed on theother side thereof to produce a projected driving beam pattern oflaterally elongated form with the lefthand end of the pattern being ofsubstantially less depth than the right-hand end thereof.

9. An electric incandescent filament lam for projectors comprising anelongated coil lighting beam filament provided with turns of differentdiameters at certain parts thereof with the whole thereof disposed inthe vicinity of a point of the lamp axis, and said coil being disposedat an angle to, and passing through, the axis of the lamp with the turnsof different diameters making the filament unsymmetrical with respect tosuch axis.

10. An electric incandescent lamp for electric projectors embodying anelongated coil lighting beam filament embodying at least two partshavbeam filament embodying at least two longitudi-' nally disposed partshaving turns of different diameters with the whole thereof disposed inthe vicinity of a point of the lamp axis, said parts having a commonaxis angularly disposed with respect to the axis of the lamp, said partsmaking the filament unsymmetrical with respect to the axis of the lamp.

12. An electric incandescent lamp for electric projectors embodying anelongated coil filament embodying at least two parts having turns ofdifferent diameters, the axis of one of said parts being offset withrespect to the axis of the other.

13. An electric incandescent lamp for electric projectors embodying anelongated coil filament embodying at least two parts having turns ofdifferent diameters, said parts having axes offset along the axis of thelamp.

1 14. An electric incandescent lamp for electric projectors embodying anelongated coil filament embodying at least two parts having turns ofdifferent diameters, said parts having axes offset along the axis of thelamp with the edges of the turns of the parts forming on one side astraight line.

15. An electric incandescent filament lamp for projectors comprising anelongated coil lighting beam filament whose turns increase in diameterfrom one end to the other, said coil filament passing through, and beingdisposed at an angle to, the axis of the lamp.

16. In an incandescent lamp for electric headlamps, a continuous coildriving beam filament whose turns differ in diameter from one end to theother with the rate of change in diameter increasing from one turn tothe next.

17. In an incandescent electric lamp for headlamps, a continuous coillighting beam filament whose turns increase in diameter from one end tothe other in a uniform manner, said coil filament passing through, andbeing disposed at an angle to, the axis of the lamp.

18. In an electric incandescent lamp for headlamps, a continuous coillighting beam filament having at least two parts differing in diameterof turns, the axes of the two parts being displaced in a plane at rightangles to the axis of the lamp;

19. In an electric incandescent lamp for headlamps, a continuous coilfilament whose end portions are formed of uniform and differentdiameters with an intermediate portion of turn diameters merging intothe two end parts.

20. In an electric incandescent lamp for headlamps, a continuous coilfilament having at least two parts of different turn diameters and oneof said parts being formed with a flat side.

' 21. In an electric incandescent lamp for projector headlamps, acontinuous coil lighting beam filament of elongated form disposedcrosswise of the lamp axis but having all of its parts disposed closelyto the point of the axis at the crossing point, said driving filamenthaving end portions of different coil diameters with said portionsdisposed on'the opposite side of the axis to provide an elongateddriving beam pattern with one end thereof of substantially lesser depththan that of the other end.

' 22. An electric incandescent lamp for headlamps embodying an elongatedcoil lighting beam filament having at least two longitudinally spacedparts of turns of different diameters, said parts being disposed onopposite sides of a plane including the axis of the lamp, with the wholethereof being disposed in the vicinity of a point of the lamp axis.

23. In an electric headlamp for automobiles, a reflector, anincandescent lighting beam filament of the continuous coil typeconcentrated at the focal point of the reflector to produce a drivingbeam with a minimum of difiusion due to displacement of filament partsfrom the focal point, said filament having its end portions formed ofdifierent coil diameters with one end of the filamerit disposed on oneside of the vertical axial plane through the focal point and the otherend of the filament disposed on the other side thereof.

24. In an electric headlamp, a reflector general- 1y cf the parabolictype, a lighting beam incandescent filament of the continuous coil typein said reflector, said filament crossing the axis of the reflector atthe focal point and having end portions of different coil diameters withat least the extreme end portions of the filament disposed on oppositesides of the vertical axial plane passing through the focal point of thereflector to produce a projected driving beam pattern of laterallyelongated form with one end of the pattern being of substantially lessdepth than the other end thereof.

25. In an electric headlamp, a reflector generally of the parabolictype, a coiled incandescent filament light source located in thevicinity of the focal point of the reflector and having portions thereofof substantially difierent coil diameters with at least the extreme endparts of said source disposed on opposite sides of the vertical axialplane passing through the focal point of the reflector to produce aprojected passing beam pattern of a laterally elongated form with therighthand end of the pattern looking in the direction of travel being ofsubstantial depth to light up the righthand side of the road to aconsiderable vertical depth and with the lefthand end of the patternbeing of substantially less depth to minimize glare to approachingdrivers.

26. An electric incandescent projector lamp comprising a reflector andan elongated coil as the light source having turns of differentdiameters at certain parts thereof, said coil being disposed in thevicinity of the focal point of the reflector and transversely of andunsymmetrical to the longitudinal axis thereof.

27. An electric incandescent lamp for projectors having an axial lampmount to produce a focused light beam, comprising an elongated coiledfilament disposed transversely of the base of said lamp, said filamenthaving turns of different diameters at certain parts thereof andunsymmetrically located relative to the longitudinal axis of the base.

28. An electric incandescent lamp for projectors, comprising anelongated coiled filament with the turns increasing in diameter from oneend to the other, said filament disposed transversely of the axis of thebase of the bulb and in the vicinity of a point thereon whereby saidlamp cooperates with the projector toproduce a beam of light ofelongated cross-section wherein one end portion thereof is substantiallydeeper than the remaining portion.

29. An incandescent projector lamp having a coiled incandescentfilament, said filament comprising at least two portions of differentdiameter. whose longitudinal axes are substantially parallel anddisposed transversely of the longitudinal axis of the base part whichextends through the focal point of the projector, said filament aXesbeing adjacent said focal point whereby an unsymmetrical focused lightbeam is produced.

30. An electric light projector in combination a reflector, and anelongated light source disposed transversely of the longitudinal axis ofthe reflector, said light source having different size light producingareas at different parts thereof to produce a beam of lightunsymmetrical to the axis.

31. An electric light projector comprising a reflector, an elongatedfilament in said reflector disposed transversely of the longitudinalaxis there of, said filament having turns of different diameters atdifferent parts thereof and supporting and electrical connecting meansfor the filament extending through and positioned in the rear of thereflector for connection to an electric circuit.

REGINALD K. BRAUNSDORFF.

file of this patent! UNITED STATES PATENTS Number Name Date 379,770Edison Mar. 20, 1888 1,157,995 Mack-ay Oct. 26, 1915 1,402,374 PapiniJan. 3, 1922 1,436,807 Jaeger Nov. 28, 1922 1,640,288 Nicholson Aug. 23,1927 1,704,467 Engle Mar. 5, 1929 1,707,540 Riedel Apr. 2, 19291,811,782 Duncan, Jr June 23, 1931 1,859,601 Rice May 24, 1932 2,067,129Marden Jan. 5, 1937 2,128,461 Johnson Aug. 30, 1938 FOREIGN PATENTSNumber Country Date 55,038 Denmark July 18, 1938 200,850 Great BritainJuly 17, 1923 228,366 Great Britain Feb. 5, 1925 246,504 Great BritainMay 13, 1926 297,052 Great Britain July 24, 1928 454,129 France Apr. 21,1913 648,455 France Aug. 13, 1928

